This could be a serious matter, but at the same time could be nothing as well. I have done a small research on this and ghere are some points you need to consider:
1- If you head the ball a lot during the game ( or even a single wrong heading ), it might cause you this pain in addition to nausea sometimes. Try to play a game without heading the ball and note if you have the same pain.
2- If you do not drink while playing, especially in hot weather, you will have dehydration which causes a headache for hours after the game. Make sure you drink lots of water while playing football.
3- If the pain happens often and lasts for 24-48 hrs, you need to consult your doctor as this could be a serious matter. If you have a stiff neck aftter the game, you definitly need to check with your physician urgently. As it could be a hemorage from a broken blood vessel.
Hi you may have a thyroid problem.You need to have it check.The thyroid helps to control the body's temp.If it is not correct it can cause your body heat to get to hot,and also cause your blood pressure to raise this can give you a bad headache.I would have it check asap.and also have your blood pressure check after you play a game.Good luck!
I've experienced the same things. Turns out I wasn't drinking enough water or eating enough calories before exercising. Could that be all the problem is for you?